During denitrification, nitrate removal may be accompanied by emissions of which greenhouse gas?

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Denitrification is a microbial process that reduces nitrate to nitrogen gases under low-oxygen conditions, using nitrate as an electron acceptor. As nitrate is progressively reduced, nitrite, nitric oxide, nitrous oxide, and finally dinitrogen gas can be formed. If the reduction stops at nitrous oxide, this gas can be released to the atmosphere. Nitrous oxide is a potent greenhouse gas with a much higher warming potential than CO2, so emissions during incomplete denitrification are environmentally important. The other gases listed aren’t directly produced by denitrification: methane comes from other anaerobic processes, ozone forms in the atmosphere from complex reactions involving NOx and VOCs, and water vapor’s abundance is tied to humidity and temperature rather than being a direct byproduct of denitrification.